In all eukaryotic cell types, protein elongation is a critical and energetically expensive step in the synthesis of new proteins. The rate of protein elongation is therefore strictly regulated to coordinate the availability of resources (energy, amino acids) with the demand for newly synthesised proteins. Eukaryotic elongation factor 2 (EF2) is essential for protein elongation: its affinity for the ribosome, and hence protein elongation rate, is controlled by its phosphorylation state. Phosphorylation of eEF2 at Threonine 56 by the elongation factor 2 kinase (EF2K or eEF2K) decreases the affinity of EF2 for the ribosome, and reduces protein elongation rates (Browne et al., Eur J Biochem. 2002, 269(22):5360-5368). This regulation is critical under various forms of cellular stress, such as nutrient limitation and hypoxia, or conditions of increased energy expenditure, such as muscle exercise. In addition, local subcellular regulation of EF2 phosphorylation by EF2K at nerve growth cones or at the synapse ensures preferential translation of certain nerve growth factors and neurotransmitters. Dysregulation of EF2 (Thr56) phosphorylation has been associated with several devastating pathologies, including cancer and depression. Tumour cells often experience various forms of stress (hypoxia, nutrient deprivation), and therefore activate eEF2K activity to balance protein elongation rates with the high demand for de novo protein synthesis. Indeed, EF2 is highly phosphoryated in tumour tissue compared to normal tissue as an adaptive response to nutrient limitation (Leprivier et al., Cell 2013, 153(5):1064-1079). Deregulation of this control through inhibition of eEF2K is thought to fatally increase energy expenditure in tumour cells, and represent an anti-tumour strategy through induction of metabolic crisis (Hait et al., Clin Cancer Res. 2006, 12:1961-1965; Jin et al., J Cell Sci. 2007, 120(3):379-83; Leprivier et al., Cell 2013, 153(5):1064-1079). Increased local translation of synaptic proteins such as BDNF (brain-derived neurotrophic factor) plays a critical role in the fast-acting anti-depressant activity of NMDA (N-Methyl-D-aspartic acid) antagonists (such as ketamine); reduced phosphorylation levels of EF2 are thought to be critical to enable BDNF translation, and hence EF2K inhibition has been proposed as a fast-acting anti-depressant therapy (Kavalali et al., Am J Psychiatry 2012, 169(11):1150-1156). Consistent with its role under hypoxia and starvation, EF2K is activated by direct phosphorylation by AMPK, whereas EF2K is regulated through inhibitory phosphorylation by growth and cell cycle kinases, such as S6K and CDK2. In addition, EF2K is a Ca2+/calmodulin-dependent kinase; this regulation may be key for the synaptic regulation of EF2K. (Browne et al., Eur J Biochem. 2002, 269(22):5360-5368).
EF2K is an atypical kinase: the primary sequence of its catalytic domain is only remotely related to that of canonical kinases, such as serine/threonine kinases, tyrosine kinases, or lipid kinases. Compounds with EF2K inhibitory activity, may prevent the stress-induced phosphorylation of eEF2 in cells and in xenografted tumours in mice. In addition to strict regulation of protein synthesis under cellular stress as described above, many cell types utilize autophagy as a recycling mechanism to cope with low nutrient availability, hypoxia and other forms of cellular stress. Autophagy is a catabolic process, in which cytosolic content, including proteins, protein aggregates and entire organelles are engulfed in vesicles (autophagosomes) which fuse to lysosomes to enable degradation of macromolecules to recuperate building blocks (amino acids, fatty acids, nucleotides) and energy (Hait et al., Clin Cancer Res. 2006, 12:1961-1965). The double membrane of autophagosomes critically consists of phosphatidylinositol-(3)-phosphate [PI(3)P], the product of the class III PI3K, Vps34 (also called PIK3C3). Vps34, and the adaptor protein, Beclin1, are both essential for autophagy in mammalian cells (Amaravadi et al., Clin Cancer Res. 2011, 17:654-666). Autophagy is upregulated in tumors, and inhibition of autophagy using the lysosomotropic agent, chloroquine (which inhibits the fusion of lysosomes to autophagosomes), or RNAi approaches can impair tumorigenesis. Moreover, inhibition of autophagy has been shown to sensitize tumors to chemotherapeutic agents, radiation, proteasome inhibitors, and kinase inhibitors (such as the receptor tyrosine kinases EGFR, class I PI3K, mTOR, and Akt) (Amaravadi et al., Clin Cancer Res. 2011, 17:654-666). The clinical utility of chloroquine in treating patients with malaria, rheumatoid arthritis, lupus and HIV suggest potential utility of autophagy inhibitors for those pathologies as well (Ben-Zvi et al., Clin Rev Allergy Immunol. 2012, 42(2):145-53). Inhibition of the class III PI3K, Vps34, may inhibit autophagy in cancer cells under stress. Moreover it was found that cancer cells, partially deficient in autophagy through knockdown of Beclin, are especially sensitive to Vps34 inhibition, suggesting that autophagy-deficient tumors (e.g. because of mono-allelic deletion of beclin1, as frequently found in breast, ovarian and prostate cancer, or other genetic lesions (Maiuri et al., Cell Death Differ. 2009, 16(1):87-93) may be most susceptible to Vps34 inhibition.
WO 2009/112439 describes 4-aryl-2-anilino-pyrimidines as PLK kinase inhibitors.
There is a strong need for novel compounds which have EF2K inhibitory activity and optionally also have Vps34 inhibitory activity, thereby opening new avenues for the treatment of cancer. It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. It is accordingly an object of the present invention to provide such novel compounds.